The knitting industry uses, for manufacture of garments, various compacted knitted textile fabrics of different constructions generally accepted as having been shrink-proofed. For such compressive shrink-proofing, two-pass types of compactors have been in vogue, as disclosed in each of U.S. Pat. Nos. 4,689,862 and 5,655,275; which compactors are typical of machines used for knitted fabric made of natural and/or man-made fibers. Although these compactors produce generally acceptable shrink-proofing results, they are temperamental and require frequent re-adjusting of their compression zones.
U.S. Pat. No. 5,016,329 uses two stationary opposing blades to form a compression zone. A fabric being compacted is required to change direction abruptly on entering and exiting a compression zone. Applicant""s GULL-WING brand compactor, disclosed in U.S. Pat. No. 5,012,562, employs a compression zone consisting of an apex (or nadir) of a stationary notched shoe and an opposing impact blade with the fabric being compacted required to make a xe2x80x9cVxe2x80x9d turn in passing through a compression zone. Common to the prior art compactors presently used for shrink-proofing knitted textile fabrics is a requirement for an abrupt change of direction of fabrics due to an organized obstruction in their respective compression zones. The abrupt change of direction contributes to jamming, for example, at the apex of the GULL-WING brand compactor. A single-pass in-line compression zone introduced in Applicant""s present invention eliminates the abrupt change of direction to render the compactor of the present invention more operator-friendly, knit-friendly and produces trouble-free superior shrink-proofing on a wide variety of constructions of knitted textile fabrics and other fabrics having characteristics kindred to knitted textile fabrics.
Compressive shrink-proofing of knitted textile fabrics, formed from interlocked loops of yarns made usually of natural fibers or man-made fibers had its origin in shrink-proofing of woven textile fabric webs. With increased popularity of knitted garments, compressive shrink-proofing of knitted textile fabrics evolved from prior experience obtained by working with flat woven textile fabric webs. Woven textile fabrics webs are rectilinear grids of threads having longitudinal warp threads interwoven by transverse fill threads. Emphasis in compaction for shrink-proofing of woven textile fabric webs naturally focused on a need for longitudinal compression. The woven textile fabrics were and are manufactured in such continuous webs which inevitably get stretched lengthwise while being woven, transported and processed. So it was and is logical, convenient and effective to shrink compressively the woven fabric webs in a longitudinal direction along their continuous webs. However, knitted textile fabrics, like randomly deposited fabrics made of natural or man-made fibers, are neither formed nor structured similarly to woven textile fabrics.
Knitted textile fabrics, for example, are composed of yarns, usually of natural fibers, formed in interlocking curvilinear loops which are arranged in stitch rows sometimes aligned perpendicularly to and sometimes skewed from perpendicular orientations relative to alignment of their continuous webs. The loops generally interlock with each other substantially at right angles (orthogonally) to their respective stitch rows. It is sometimes convenient to visualize stitch rows ideally as being straight and aligned transversely relative to a longitudinal path of the fabric, like soldiers marching on parade through their compactor. Yet such an ideal image of stitch rows through a compactor rarely finds its counterpart in the real world. Knitted textile fabrics frequently are not designed with straight transverse stitch rows. Handling and treatment of knitted textile fabrics, warp, bend, twist and otherwise distort their stitch rows. Further, the stitch rows themselves are formed as a progression of repeating series of curvilinear loops of yarn. So as far as compacting of knitted textile fabrics is concerned, terms such as xe2x80x9cstraightxe2x80x9d or xe2x80x9calignedxe2x80x9d stitch rows are wishful euphemisms.
A loop of yarn in a knitted fabric actually exhibits behavior characteristics quite different from those that logically might be expected from an ideal image of stitch rows. Applicant examined behavioral characteristics of actual knitted structures as they undergo compaction, so as to deal with on their own terms with the loops and stitch rows as they actually exist in the real world.
The knitted textile fabrics, when composed of natural fibers, typically are manufactured in the form of continuous tubes which are then flattened and compacted in a longitudinal direction analogous to compacting of woven textile fabrics. Alternately the knitted tubes may be split open, spread and subjected to longitudinal compacting as open webs. Knitted textile fabrics, with small loops or fine yarns making up the loops, require compaction as open webs. As has been noted herein, technology which evolved from compacting of woven textile fabric webs generally has achieved inconsistent success in treating knitted textile fabrics. Lack of consistent success has been common to compaction of knitted textile fabrics both as tubes and as open webs. Accordingly some people look upon compressive shrinking of knitted fabrics as an occult art.
In actual knitted textile fabrics we frequently can expect unreliable orientation (skewing) of stitch rows formed of interlocked yarn loops. An alignment of the loops has been recognized by Applicant to occur orthogonally each individual loop relative to its related skewed stitch row. Applicant""s recognition, acceptance and accommodation of the skewed orientation of the stitch rows and inherent behavior of the loops relative to their respective stitch rows are at a crux of Applicant""s successful, consistent and reliable compacting of knitted textile fabrics and other similar fabrics made of natural and/or man-made fibers. It followed that organizing apparatus and a related method for freeing the interlocked loops of yarn to move easily, as they naturally choose, toward each other orthogonally relative to their skewed stitch rows opened the door to Applicant""s success.
Effective compressive shrink-proofing of knitted textile fabrics of natural fibers depends in part on expansion of heated and/or moistened yarn caused by partial unraveling of their fibers. Steam puffing and lubricating effects on nautral yarn loops of knitted textile fabrics are discussed in Applicant""s U.S. Pat. No. 4,447,938 whose disclosure is included herein by reference. Another reality of compaction is that the fabric reduces in volume by mechanical pushing of the interlocked loops of yarn preferably toward each other. The present invention focuses on the mechanical pushing action.
The loops interlock generally at right angles (orthogonally) each relative to its related stitch row. With the stitch rows unreliably organized, and the yarn loops arranged orthogonally thereto, application of longitudinal compaction through a crimped, bent, kinked or otherwise obstructed compression zone was effective along a series of longitudinal vectors from a continuum of points along a curvilinear loop of yarn. Simultaneously, a series of companion transverse vectors of any or all of the same points could thereby be either wasted or they could contribute to counterproductive stretching. Accordingly a substantial portion of longitudinal compacting effort on knitted textile fabrics was self-defeating when performed through the crimped, bent, kinked or otherwise obstructed compression zones of the prior art. By eliminating abrupt direction change, due to obstruction, as the web of knitted fabric passes through the compression zone, Applicant frees the loops each to move according to its own natural preference, which he recognized to be orthogonally relative to its related stitch row, unaffected by likely skewed orientations of the stitch rows that make up the web of knitted fabric.
Applicant here approaches compacting of knitted textile fabrics by delivering and removing a confined web of the fabric, usually heated and/or moistened, through a substantially in-line compression zone wherein the loops of yam of the fabric web, while expanding due to partial unraveling, are allowed to reduce in volume by the loops being pushed together each according to its own natural preference orthogonally relative to a skewed axis of its respective stitch row. By eliminating crimps, bends, kinks and other obstructions at the compression zone, Applicant avoids limiting the compacting effort to being only longitudinally directed relative to the fabric web and thus Applicant avoids the counterproductive stretching. Employing this approach Applicant allows the expanding loops to move as they choose according to inherent influences of their composition, history and knitted structure in the easiest and most natural way they can find so as to each reduce its own volume. By this teaching, the direction of movement of the interlocked yam loops is toward each other orthogonally relative to their respective stitch rows, independent of how bent, warped, twisted or otherwise skewed those stitch rows may be.
Because of Applicant""s novel, useful and non-obvious approach, his present apparatus is inexpensive to build, easy to operate and more reliable than apparatuses of the prior art. He achieves operator-friendly, knit-friendly, superior and more reliable compaction of knitted textile fabrics and similar fabrics than has heretofore been achievable. His compactor contributes toward its goal by eliminating counterproductive tensions. He achieves his objective without polishing, crimping or grabbing of the knitted fabric. Applicant""s apparatus and related method for shrinking of knitted textile fabrics made of natural fibers also is applicable to fabrics made from manmade fabrics, non-woven textiles, papers, papers with additives, and the like; because their formations and structural characteristics are generally random and much more similar to those of knitted textile fabrics than they are to those of woven textile fabrics. Further, Applicant""s invention is easily retrofittable into a wide variety of existing compressive shrink-proofing apparatuses. Single-station double-roller compressive shrink-proofing apparatuses are the most likely candidates for retrofitting.
It is therefore an object of the present invention to provide an apparatus and related method to produce superior-quality controlled permanent compaction of knitted textile and similar fabrics.
It is a further object of the present invention to provide an in-line, short smooth compression zone without bends, crimps, kinks or similar obstructions.
It is a further object of the present invention to provide setting of gap width by moving either a feeding surface or a retarding surface toward or away one from the other, for example, by moving either a retarding roller or a feeding roller toward or away from the other, or by moving one endless belt toward or away from a companion endless belt.
It is a further object of the present invention to provide resilient loading against the fabric for example by applying pneumatic pressure onto confining shoes.
It is a further object of the present invention to provide apparatus to maintain the fabric in dual frictional engagement with either a feeding surface (on one side of the fabric) or a retarding surface (on the other side) in tandem, not simultaneously so as to avoid polishing, crimping or grabbing of the knitted fabric. Alternately the fabric can be introduced in engagement with an entry roller and then discharged in engagement with a retarder roller.
It is a further object of the present invention to treat evenly both sides of a tube of the knitted and similar fabrics.
It is a further object to provide apparatus for carrying out the present invention which apparatus is easily retrofittable into a wide variety of existing compressive shrink-proffing apparatuses.
It is a further object of the present invention to treat effectively tubular knitted fabrics avoiding sidedness of the finished fabric.
It is a further object of the present invention to shrink compressively knitted and similar fabrics free from counterproductive tension.
It is a further object of the present invention to shrink compressively knitted textile fabrics in a single pass.
It is a further object of the present invention to shrink compressively knitted and similar fabrics free from scorching, polishing, crimping and grabbing.
It is a further object of the present invention to accommodate compacting of knitted textile fabrics or similar fabrics in either closed tubes or open webs.
It is a further object of the present invention to provide an apparatus and a related method to accommodate fabrics of natural or man-made fibers.
It is a further object of the present invention to provide an apparatus and a related method that, in addition to knitted fabrics, likewise is usable for non-woven textiles, papers, papers with additives, and the like.
It is a further object of the present invention to provide an apparatus which accommodates automatic operational features including programable logic control.
It is a further object of the present invention to apply compaction optimally for volumetric reduction of knitted textile and similar fabrics.
It is a further object of the present invention to allow interlocked loops of knitted fabrics to compact by movement of their loops orthogonally each relative to its related stitch rows which may be skewed, bent, warped and/or twisted.
It is a further object of the present invention to accommodate expansion of fibers of the knitted fabric by application of heat and/or moisture thereto. The fibers puff and partially unravel as the loops move toward each other.
It is a further object of the present invention to set and hold compaction that has been achieved.
It is a further object of the present invention to provide an apparatus that is inexpensive to build, is versatile and reliable; as well as to present a related method that is simple and easy to operate and to adjust.
It is a further object of the present invention to provide an apparatus and related method that are knit-friendly and operator-friendly producing knitted textile fabrics and similar fabrics which are manufacturer-friendly and most of all wearer-friendly.
It is a further object of the present invention to accommodate compaction of the widest variety of knitted fabrics including sensitive fabrics, gauze materials and the like.
It is still further object of the present invention to reduce power requirements of the apparatus.
It is a further object of the present invention to conserve space requirements of the apparatus.
Applicant achieves the foregoing objectives by providing a compressive shrinking apparatus and related method for a web or a tube of knitted textile fabric of natural and/or man-made fibers, or of a similar fabric, With a retarder surface moving at a substantially lower surface speed than the surface speed of a paired entry surface and with a compression zone formed between the surfaces. Width of a gap in the compression zone can be controlled by movement of the retarder surface and/or the entry surface toward or away from each other and by resilient loading applied thereto. The compression zone is arranged to be in-line and unobstructed. The web of fabric is contained preferably resiliently as it is passed from the feeding surface into the compression zone, through the compression zone and as it leaves the compression zone. The fabric preferably is heated and pre-moistened and the surfaces preferably are heated.